Phase shifter



I Sept. 24, 1946. 5 E 2,408,193

PHASE SHIFT'ER Filed Dec. 6, 1943 arrow/Er Patented Sept. 24, 1946 PHASE SHIFTER Harold Edward Beste, East Rutherford, N. J assignor to Allen B. Du Mont Laboratories, Inc., Passaic, N. J., a corporation of Delaware Application December 6, 1943, Serial No. 513,136

4 Claims.

This invention relates to a phase shifter which comprises a transformer of which the primary is in the cathode circuit of a vacuum tube.

The invention may be understood from the description in connection with the accompanying drawing, in which reference character I indicates a connection from a source of alternating current which may, for example, be of a frequency of 100 c. p. s. The terminal 1 is coupled by condenser 2 to the grid of triode 3 which has grid leak '4. The cathode 5 of tube 3 is connected to one end of the primary 6 of transformer l, the other end of, which is grounded.

Two like coils 8 and 9 connected in series and grounded at the center it constitute the secondary of the transformer l. The lower end of the secondary 9 is connected to one end of a variable resistance H, and the upper end of the coil 8 is coupled by condenser IE to the upper end of resistance II. A sliding contact II is provided to vary the portion of the resistance H 7 that is in the circuit.

A condenser 13 couples the phase shifter through resistance Id to the control grid of triode l5, this grid being provided With a grid leak IE to ground. The cathode of tube I5 is connected to the cathode of tube l6, and both are connected to ground through resistance IT. A lead 18 extends from a source of positive potential through load resistances l9 and 20 to the plates of the tubes l5 and I5. And this lead I 8 is also connected through resistance 2| to the screen grids of the tubes l5 and H5 in the usual way.

The tubes l5 and I6 and connections constitute or provide a balanced phase-inverter deflection amplifier, from which signals of opposite polarity can be taken and coupled by condensers 22, 23 and leads 24, 25 to a pair of deflection plates of an oscillograph cathode-ray tube not shown.

The oscillations fed in at I and applied by tube 3 pass through the primary 6 of transformer 1, setting up voltages in the coils 8 and 9 which the condenser I 2 and the portion of resistance II that is in series across the secondary 8, 9 of the transformer I. When the contact II is at the lower end of resistance II, the voltage at the grid of tube I5 is approximately ahead of that across the secondary 8, 9, and the more of the resistance II that is placed in the circuit by moving contact ll closer to the upper end of resistance II the nearer the voltage at the grid of tube I5 is in phase with the voltage across the secondary 8, 9.

The current through the coil 6 is not dependent upon the phase or amount of current through the coils-8 and 9, as this current depends primarily upon the voltages at the grid and plate of tube 3.

Due to the comparative low impedance and high current in coil 6, any change in phase due to adjustment of contact l I results in very little, if any, change in voltage output of this phase shifter.

What is claimed is:

1. In an electronic device for shifting the phase of voltage, a vacuum tube to the control grid of which said voltage is to be applied, and a transformer having its primary connected between the cathode of said tube and ground, the ends I of the secondary of said transformer being connected to a resistance and capacitance in series.

2. The device of claim 1, in which said resistance is variable.

3. The device of claim 1, in which an output lead is connected between said resistance and capacitance.

4. The device of claim 1, in which said secondary is grounded.

' HAROLD EDWARD BES'I'E. 

